The disclosed embodiments of the present invention relate to converting a multi-view video stream into a polarized video stream, and more particularly, to an apparatus and method for generating a polarized video stream according to a multi-view video stream (e.g., a stereo/three-dimensional video stream carrying left-eye images and right-eye images) and motion information derived from the multi-view video stream.
With the development of science and technology, users are pursing stereoscopic and more real image displays rather than high quality images. There are two techniques of present stereo video display. One is to use a video output apparatus which collaborates with glasses (such as anaglyph glasses, polarization glasses or shutter glasses), while the other is to directly use a video output apparatus without any accompanying glasses. No matter which technique is utilized, the main theory of stereo video display is to make the left eye and the right eye see different images, thus the brain will regard the different images seen from two eyes as stereo images.
For shutter glasses, they are widely used for users to view stereo images presented by a video output apparatus. The shutter glasses include two shutter lenses, and allow user's left eye to see left-eye images and user's right eye to see right-eye images by properly switching the shutter lenses between an open state and a close state. However, as a pair of shutter glasses is required to have a controller disposed thereon to control the states of shutter lenses and a battery module disposed thereon to supply power to the controller and the shutter lenses, the cost of shutter glasses is high.
The polarization-based stereo video display technique may be employed due to its lower implementation cost. For example, to display a stereo video on a panel viewed by a user, one polarization-based method is to use a pattern retarder (PR) type or micro retarder type panel. Therefore, an original stereo video stream, including left-eye images and right-eye images, should be converted into a polarized video stream to be properly displayed on the PR type/micro retarder type panel for presenting stereo images to the user. One conventional method is to extract half of scan lines of a left-eye image, extract half of scan lines of a right-eye image, and generate a polarized video frame by combining the extracted scan lines. However, the resolution of the stereo image displayed on the PR type/micro retarder type panel driven by such a polarized video stream is reduced to half of that of the stereo image displayed on a panel driven by the original stereo video stream.
To increase the resolution of the polarized stereo display, a higher temporal frame rate may be employed. That is, the polarized video stream includes more than one frame in an original frame period (e.g., 1/60 second) of left-eye frames and right-eye frames included in the stereo video stream. A conventional method for achieving the higher temporal frame rate is to generate one frame by gathering even scan lines of a pair of left-eye image and right-eye image and generate another frame by gathering odd scan lines of the same pair of left-eye image and right-eye image. However, such a conventional design only has good display quality for frames having motion in a specific direction due to a fixed scan line selection order. Regarding frames having motion in other directions or frames that are still images having no motion, the polarized stereo display with a higher temporal frame rate suffers from the flickering problem and has degraded display quality.